Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China.
Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China; School of Radiation Medicine and Protection (SRMP), School for Radiological and Interdisciplinary Sciences (RAD-X), Suzhou 215000, PR China.
J Hazard Mater. 2015 Apr 28;287:42-50. doi: 10.1016/j.jhazmat.2015.01.030. Epub 2015 Jan 13.
The mechanism of the isotope exchange reaction between molecular tritium and several typical organic molecules in vacuum pump mineral oil has been investigated by density functional theory (DFT), and the reaction rates are determined by conventional transition state theory (TST). The tritium-hydrogen isotope exchange reaction can proceed with two different mechanisms, the direct T-H exchange mechanism and the hyrogenation-dehydrogenation exchange mechanism. In the direct exchange mechanism, the titrated product is obtained through one-step via a four-membered ring hydrogen migration transition state. In the hyrogenation-dehydrogenation exchange mechanism, the T-H exchange could be accomplished by the hydrogenation of the unsaturated bond with tritium followed by the dehydrogenation of HT. Isotope exchange between hydrogen and tritium is selective, and oil containing molecules with OH and COOH groups can more easily exchange hydrogen for tritium. For aldehydes and ketones, the ability of T-H isotope exchange can be determined by the hydrogenation of T2 or the dehydrogenation of HT. The molecules containing one type of hydrogen provide a single product, while the molecules containing different types of hydrogens provide competitive products. The rate constants are presented to quantitatively estimate the selectivity of the products.
运用密度泛函理论（DFT）研究了真空中分子氚与几种典型有机分子间同位素交换反应的机理，并通过传统过渡态理论（TST）确定了反应速率。氚-氢同位素交换反应可通过两种不同的机制进行，即直接 T-H 交换机制和加氢-脱氢交换机制。在直接交换机制中，通过四元环氢迁移过渡态一步即可得到滴定产物。在加氢-脱氢交换机制中，T-H 交换可通过与氚的不饱和键加氢，随后 HT 脱氢来完成。氢和氚之间的同位素交换具有选择性，含有 OH 和 COOH 基团的油分子更容易将氢交换为氚。对于醛和酮，T-H 同位素交换的能力可以通过 T2 的加氢或 HT 的脱氢来确定。含有一种类型氢的分子提供单一产物，而含有不同类型氢的分子则提供竞争产物。给出速率常数以定量估计产物的选择性。
